Lubricating grease compositions



Unite tates atent O LUBRICATING GREASE COMPOSITIONS Arnold J. Morway, Clark, N.J., assignor to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Apr. 1, 1955, Ser. No. 498,743

8 Claims. (Cl. 252-35) This invention relates to novel organo-metallic complexes or compounds with coordinated valences and to compositions containing the same. More particularly, the present invention pertains to soap-salt complexes comprising a metal salt of acetic acid, a metal salt of medium molecular weight carboxylic acid, and a metal soap of high molecular weight carboxylic acid, to methods for preparing the soap-salt complexes and to cmpositions containing them.

In brief compass, the invention relates to compositions consisting of or containing dehydrated and baked complexes or coordinated compounds consisting of a metal salt of acetic acid, a metal salt of a medium molecular weight carboxylic acid containing from about 3 to carbon atoms, and a metal soap of a high molecular weight monocarboxylic acid containing from about 12 to 30 carbon atoms and preferably 18 to 22 carbon atoms, in which the mol ratio of acetic acid to the other acids employed exceeds 4, and in which the difference in number of carbon atoms per molecule between the average of the high molecular weight carboxylic acids and the average of the medium molecular weight carboxylic acids is at least 7. A lower mol ratio of acetic acid to the other acids may be used if the average saponification number of all the other acids exceeds 320 mgs. KOH per gm. The compositions of the invention include novel and improved lubricating greases, lubricating oils, gear oils, filter oils, etc. In particular, grease compositions containing the complexes of the invention have been found to have excellent extreme pressure and structural stability properties as well as other desirable grease characteristics.

The use of so-called soap-salt complexes as grease thickeners is well known in the art. The complex materials used heretofore consisted of combinations of metal soaps of high molecular weight carboxylic acids having from 12 to 30 carbon atoms and metal salts of low molecular weight carboxylic acids containing from 1 to 6 carbon atoms per molecule. The commonly known grease-making, high molecular weight fatty acids, saturated or unsaturated, containing from about 12 to 22 carbon atoms have been employed in conjunction with such low molecular weight carboxylic acids as acetic, propionic, alkoxy propionic, and the like to form the complex grease thiekeners of the prior'art. Normally.

about equimolar proportions of low to high molecular weight carboxylic acids have been employed by the prior art, because of the limited thickening effect of the low molecular weight carboxylic acid component. High- 1y desirable characteristics recently have been imparted "ice to compositions of that sort by drastically increasing the low molecular weight acid content, and with it the metal content of the soap-salt complexes, so that they contain at least 7 moles and up to 40 moles or more of the low molecular weight acid per mol of the high molecular weight acid.

It has now been found that novel compounds which are true complexes can be prepared by employing a metal salt of acetic acid, at least one metal salt of a medium molecular weight carboxylic acid, and at least one metal salt of a high molecular weight carboxylic acid. In accordance with the invention, the difference in' average number of carbon atoms per molecule between the high and the medium molecular weight carboxylic acid should be at least 7 and the average saponification value of the carboxylic acids, other than acetic acid should be within the range of about 290 to 450 and preferably at least 320. It has also been found that when the combination of acids described above is employedwith the stated carbon atom spread, a mol ratio of acetic to the other acids above 4:1 and as high as 40:1 can be effectively utilized to prepare the novel complex compounds of the invention. When" lower mol ratios are desired, the average saponification number of the medium and high molecular weight acids must exceed 320.

For the purposes of this invention, carboxylic acids containing from about 3 to 10 and preferably 6 to 9 carbon atoms per molecule are designated as the medium molecular weight carboxylic acids. Those having from 6 to 9 carbon atoms are preferred. If it is desirable to use a polycarboxylic acid as the medium molecular weight acid in accordance with this invention, its saponification number must be reckoned on the basis of its molar equivalence in monocarboxylic acid. The equivalent saponification number is the quotient of milligrams equivalent weight of KOI-I (or 56,100) and gram equivalent of the acid. Suitable carboxylic acids coming within this definition are exemplified by the following:

Straight chain saturated aliphatic carboxylic acids:

Pentanoic (Valerie) a Hexanoic (caproic) Heptanoic (enanthic) Octanoic (caprylic) Nonanoic (pelargonic) Decanoic (capric) Branched chain saturated aliphatic acids:

lsobutyric C5 OX0 C8 OX0 Hydroxy aliphatic monoand poly-carboxylic acids: Glyceric Lactic, sap.'No. 623 Citric, sap. No. 267, equv. sap. No, 801

Aromatic mono-and poly-carboxylic acids and anhydrides: a

Benzoic Hydroxy benzoic Toluic o-Phthalic (sap. No. 338; equiv. sap. No. 676) Phthalic anhydride, Terephthalic Heterocyclic acids:

Furoic Thiophene carboxylic Mixed as well as single medium molecular weight carboxylic acids may be employed in accordance with the foregoing statements about the average carbon atom spread and average minimum saponification number of the high and medium molecular weight carboxylic acids. Similarly, commercial mixtures of medium molecular weight carboxylic acids can also be utilized to prepare the novel complexes.

The Oxo acids useful for the purposes of the present invention, e.g. the saturated branched chain C to C Oxo acids, can be prepared by means of the well known Oxo synthesis. This process involves the oxona-tion or carbonylation of olefins with carbon monoxide and hydrogen at elevated temperatures of about 300 to 400 F. and pressures of about 2500 and 4000 p.s.i.g. in the presence of a group VIII catalyst, preferably cobalt. In Us. Patent No. 2,632,021 the Oxo process and the nature of the reaction products, e.g. 0,; x0 products, are disclosed in detail. The preparation of acids from the 0x0 reaction products is described in US. Patent No. 2,537,577 and U3. Patent No. 2,553,364. Neither the preparation of the 0x0 reaction products nor the preparation of the 0x0 acids therefrom are considered'to be essential elements of the present invention. The C Oxo acids can be derived from butylene, for example, and the C Oxo acids from the C olefins produced by polymerizing propylene alone or with some butylene.

High molecular weight monocarboxylic acids containing from about 12 to 30, preferably from 18 to 22, carbon atoms are useful for the purposes of this invention. These acids may be derived from saturated or unsaturated naturally occurring or synthetic fatty material. The fatty acids normally used in the manufacture of conventional greases, particularly the more saturated acids, are preferred. Examples of such acids include lauric, myristic, palrnitic, stearic, mono-hydroxy stearic, di-hydroxy stearic, poly-hydroxy stearic and arachidic acids and the hydrogenated fish oil and tallow acids, which contain chiefiy stearic acid. However, unsaturated acids such as oleic, ricinoleic and similar acids may also be used. The average saponification value of a mixture of the high molecular weight carboxylic acids useful for the purposes of the present invention should not be more than about 280 and is preferably not more than about 220.

The acetic acid employed in the present invention can be either glacial acetic acid or an aqueous solution of acetic acid. The concentration of acid in the solution may vary from about 60 to 99.9 wt. percent, and is preferably about 80 wt. percent. The presence of a salt of acetic acid in the complex is an essential part of the present invention, but the use of a'substituted acetic acid having 2 carbon atoms per molecule is not excluded, where such modification may be desirable. For example, chloro-acetic acid, glycolic acid, thioglycolic acid, glycine, or oxalic acid may be used to modify the structure of a grease made in accordance with the invention.

The metal component of the complexes of the invention is used in a form which can combine chemically with carboxylic acids to form salts or soaps; Ordinarily the metal hydroxide is used. The choice of metal component depends to a certain extent on the use to which the multiple salt and soap complex of the inventionis to be put.

The alkaline earth metal hydroxides or carbonates such as those of calcium, barium and strontium are useful for many purposes of the invention. Calcium hydroxide is especially preferred. These metals afford the greatest advantages when their complexes, with mol ratios of acetic to the medium and high molecular weight acids above 5 :1, are used as grease thickeners, since they result in the production of greases having outstanding load carrying characteristics and structural stability during storage and at high temperatures even without the use of conventional extreme pressure and stabilizing agents. The alkaline earth metals differ in this respect from the alkali metals, i.e. sodium, potassium and lithium. Soapsalt complexes having a high alkali metal content and which consist of the combination of acids, mol ratios and carbon atom spreads of this invention, yield greases.

without extreme-pressure load-carrying properties and with poor structural stability even when added to the oil dispersant in relatively high proportions. It is therefore preferred to use metals having two valences. However, when more than one metal salt or soap is used in the complex, one of them may be an alkali metal, for example, lithium.

Other metals useful for the purposes of this invention are magnesium and zinc. In some applications, wherein the metal is required to confer a catalytic effect for promoting oxidation or combustion, copper, iron, nickel or cobalt may be used. To sum up briefly, the preferred class of metals are the alkaline earth metals and zinc; and the preferred metal in that clas is calcium.

The metallic constituents of the salts and soaps may be any one or more of the metals set forth above. Though the metals may be either the same or different, in most cases the salts and soaps contain the same metal. If it is desired to incorporate a monovalent metal, e.g. lithium, into the composition along with a divalent metal, e.g. calcium, the monovalent metal should be in the salt of medium molecular weight carboxylic acid, particularly if it is a dicarboxylic acid.

In accordance with the present invention the proportion of acetic acid by weight should exceed that of the sum of medium and high molecular weight carboxylic acids; and the combination of the medium and high molecular weight acids should be selected so that the carbon atom spread, that is the difference in the average number of carbon atoms per molecule, between the high and the medium molecular weight carboxylic acids is at least about 7, preferably 7 to 15, and the average equivalent saponification value of the medium and high molecular weight carboxylic acids be within the range of about 290 to 450, and preferably above 320. When these limitations are observed, the mol ratio of acetic to the higher molecular weight carboxylic acids can be lower than 5:1 and at least 4:1; but it is particularly preferred to be higher than 5 :1 and most particularly between 7:1 and 25:1, in order to get the maximum benefit of a high content of combined metal per unit weight of the composition and therefore to get maximum utility for extreme pressure application.

The constitution and chemical nature of the complexes of this invention are not fully understood. X-ray diifraction spectra of these soap-salt complexes do show, however, patterns definitely inconsistent with that of a physical mixture of the individual salt and soap constituents. The spectra also show that the temperature employed during the preparation of the complex compounds, the mol ratio of acids, etc. will influence the type of X-ray pattern obtained. Formation of the complexes or coordination compounds occurs after the salts have been heated not merely to dehydration but to higher tempera tures., Consequently, these are anhydrous or dehydrated, baked complexes.

In accordance With one feature of the present invention, the soap-salt complexes containing a metal salt of acetic acid, at least one metal salt ofa medium molecular weight carboxylic acid having from about 3 to 10 carbon atoms, mid at least one metal soap of a high molecular weight carboxylic acid having 12 to 30 carbon atoms may be incorporated in a wide variety of liquid and semiliquid materials of natural or synthetic origin to improve the utility of these materials. In one particular embodiepraeae of excellent extreme pressure and structural stability 5 characteristics. In general, the mineral or synthetic lubricating oil should have a viscosity within the range of about 50 to 2000 SUS at 100 F. and 30 to 150 SUS at 210 F., a pour point of about +20 to 75 F., a

flash point of about 350 to 650 F., and a viscosity index of about 0 to '60 although 100 or higher is also desirable and can be employed. As mentioned above, synthetic as well as mineral lubricating oils can be employed as part of all of the liquid phase of the grease,

and they include synthetic lubricating oils of the hydro- 16 carbon, hydrocarbon polymer, ester, complex ester, formal, mercaptal, polyalkylene oxide, silicone or similar types. Synthetic oils such as di-Z-ethylhexyl sebacate, di-C Oxo, azelate and other branched chain simple esters of dicarboxylic acids can be used, as well as com- 20 plex esters prepared from glycols, dicarboxylic acids, and alcohols or monocarboxylic acids.

The metal soap-salt complexes of the invention may be prepared by coneutralization of a mixture of the carboxylic acids with suitable bases, particularly the hydroxides and/or carbonates of the metals desired. The coneutralization step may be carried out in situ in the liquid menstruum to which the complex compound is to be applied in actual use. For example, the mixed acids may be coneutralized in a portion or all of a lubricating oil which then forms the dispersant of the complex and is thereby gelled to a grease. In a similar manner, the coneutralization may be carried out in other dispersants or solvent fluids, the characteristics of which are to be modified by the complex compound. This coneutraliza- I tion method of preparation is particularly desirable in cases in which the salts and soap have the same metal constituent. The coneutralized material is heated to a temperature above about 400 F., preferably 450 to 550 F., in order to dehydrate it and to form the baked complex. When this heating step is carried out in a liquid dispersant, the latter should have a boiling point above 400 F. or heating should be carried out under pressure.

The coneutralization method of preparation is not nec- '45 essary as long as the metal salts and soap are present when heating to the complex forming temperatures. Thus, the complex compounds of the invention may also be prepared by separately preforming at least a portion of the acetic acid salt, the medium molecular weight carboxylic acid salt, and the high molecular weight carboxylic acid soap, intimately mixing the preformed ma terials, and baking the resulting mixture under complex forming conditions. This method is especially useful when different metals are employed as bases for the salts and soap.

mixing to a temperature of about to 'F., but preferably just sufficient to melt the high' molecular mixture, and allowed to react Without further external heating. When temperature of reaction starts to subside, external heating is then applied and is continued until the temperature is about 400 to 550, preferably about 450 to 550 F. At this point, heating isdis- 70.

continued and the greasebatch "is cooled to about 250 F. Any of the conventional anti-oxidant additives, such as phenyl alpha naphthylamine, are added at this time,

"and the grease is further cooled to below about 200 F. .The resulting grease composition may be homogenized 75 acid, and the medium molecular weight carboxylic acid.- Warm the mixture while mixing to a temperature of about to =l50 F. Add acetic acid to the warmed mixture, and then heat to the complex forming temperature of about 400 to 550 F. Other than adding the medium molecular weight carboxylic acid to the initial mixture rather than in admixture with the acetic acid after the Warming has taken place, this method of preparation is similar to that outlined in the preceding paragraph.

The complex compounds of the invention when prepared in a liquid dispersant or solvent may be isolated from their dispersions or solutions by solvent extraction of the dispersing medium in a solvent in which the complex is insoluble. Suitable solvents include most of the hydrocarbon solvents, acetone, etc.; the proper choice depending on the solubility characteristics of the liquid menstruum used to disperse the complex.

The invention will be more fully understood by reference to the following specific examples illustrating various modifications of the invention.

EXAMPLE I Grease N0..A

All of the mineral lubricating oil, caprylic acid, valeric acid and hydrated lime were charged to a fire heated .kettle and warmed While mixing to F. v The acetic acid was then added, and the heating was continued until the temperature reached 450 F. At this temperature the heating was discontinued, and the grease'batch was cooled to 250 F. Phenyl alpha naphthylaniine was then added, and the grease was further cooled to about 200 F. The resulting grease composition was finished by being passed through a Gaulin homogenizer at 5000 p.s.i. I

Grease No. B

All of the mineral lurbicating oil, hydrated 'lime,

stearic acid and o-phthalic acid were charged to a fire heated kettle, and the mixture was warmed to 135 F.

with thorough mixing. At this temperature all of the was then discontinued and the grease cooled to 250 F.

with stirring. Phenyl alpha naphthylamine was added to the grease batch and cooling continued to 180 F. The grease was then homogenized in a Gaulin homogenizer.

W Grease No. C

This grease, having the formulation listed below in Table I, was prepared by the method described above with, respect to the preparation of Grease A, except that C 2 weight acid. The acetic acid and the medium molecular if OX0 acld'was gmployed as the medium molecular weight weight carboxylic acid employed are then added to, the, 65

carboxylic acid and lauric acid was employed as the high molecular Weight carboxylic acid.

Grease N o. D

All of the mineral lubricating oil, hydrated lime, Hy drofol Acid 51, and lactic acid were charged to a fire heated kettle and warmed to 135 F. with stirring. The. glacial acetic acid was then added to the mixture, which n was then heated to 500 F. Heating, was then discon--" tinued, and the grease batch cooled to'250 F. At; this temperature the phenyl alpha naphthylamine was added.

Grease N0. E

8 added and the temperature raised to 500 F. Heating was then discontinued, and the grease batch was cooled to 250 F. with agitation. At this temperature, the phenyl alpha naphthylamine was added, and the greases further cooled to 200 F. The grease product was then Gaulin All of the mineral lubricating oil, stearic acid, hydrated homogemzed, filtered and Packagedlime, and thiophene carboxylic acid were charged to a Grease Na 1 fire heated grease kettle and mixed intimately while raising the temperature to 135 F. Glacial acetic acid was The mineral lubricating oil, Hydrofol Acid 51, bythen added, and heating was continued to 500 F. The 10 drated lime and benzoic acid were charged to a fire heated grease batch was held at this temperature for 10 minutes kettle and mixed together while heating to 135 F. and then cooled to 275 F. with stirring. The phenyl Acetic acid was then added, and heating continued to alpha naphthylamine was added to the grease batch, and 510 F. Heating was then discontinued, and the grease cooling was continued to 180-200 F. The resulting cooled to 250 F. while continuing to agitate. At this grease composition was then pumped to a Gaulin homogetemperature phenyl alpha naphthylamine was added, and nizer, homogenized at 6000 p.s.i., filtered and packaged. the grease batch further cooled to 180 F. while mixing. The grease product was Gaulin homogenized at 5000 Grease N F p.s.i., filtered and packaged. All of the mineral lubricating oil, hydrated lime, and stearic acid were charged to a fire heated. kettle and Grease No' I warmed to 150 F. While mixing. The isobutyric acid and This grease was prepared by the method substantially acetic acid were then added as a mixture and heating was as described in the preparation of Grease No. H. continued until the temperature reached 430-450 F. Heating was then discontinued and the grease batch cooled Grease N K to At fills temperature the Phenyl alpha P This grease was also prepared by the method substanthylamme added, and thefireasc batch furthfilf cooled tially as described in the preparation of Grease No. H, 10 200 respltmg grease composmon except that capric acid rather than caprylic acid was then finlshed by Passlng 1t through a Morehouse mm employed as the medium molecular weight carboxylic homogenizer at 5000 p.s.i. acid Grease Na G Grease No. L

The mineral lubricating oil, hydrated lime, and Hy- This grease Was also P p y the method SHbStandrofol Acid 51 were charged to a fire heated kettle and as described in the P1139211?!tion 0f Grease warmed to 135 F. with stirring. The glacial acetic acid and the C OX0 acid were then added to the mixture, and Grease M heating Continued to Heating Was then diSCOIl' All of the mineral lubricating oil, the stearic acid and fi d and the grease batch cooled to The hydrated lime were charged to a fire heated kettle and P y alpha naphthylamine s then added, and cooling heated to about 130 F. with stirring. The acetic acid was continued to 200 F At thlS temperature, thegrsase 40 was then added, and the grease mixture heated to a temproduct was P s d through a Gaulm homogemzer at erature of 500 F. Heating was then discontinued, and 3000 P- the grease cooled to 250 F. with stirring. Phenyl alpha Grease N0- H naphthylamine was added, and the grease cooled further The mineral lubricating oil, hydrated lime, Hydrofol to 200 F. The resulting grease composition was homoge- Acid 51 were charged to a fire heated kettle, and warmed IliZed at a high rate of Shea! in a Gallll'll homogenizato 150 F. while agitating. When the mixture started to The exact compositions and properties of the above thicken, a mixture of acetic acid and caprylic acid was compositions are tabulated in Table I below:

TABLE I Grease N o A B 0 Formulation (Wt. Percent):

Glacial acetic acid Valerie acid C 0x0 acid Caprylic acid... Lnuric acid... Stcaric acido-Phthalie..-. l-Iydroiol Acid 51.. 'lhiophene Cerboxylic c1 Iso butyric acid. 08 0 d Lactic acid... Hydrated lime Phenyl alpha naphthylamine Mineral lubricating oil,

55 SUS 210 F Moi ratio: Acetic acid to higher acid Equivalent Sap. No. of

acids (Ex acetic) Carbon atom spread (Medium to higher acid) Free alkalinity (percent N aOH) TABLE I-Oontinued Grease No A B o 4 D n F o H 1 J K II M" Properties:

Appearance se l S il form 7 Dropping Point F.) 500+ 500+ 500+ 500+ 500+ 500+ 500+ 500+ 500+ 500+ 500+ 500+ 500+ P711&l;latl0n5 (77 Fmm.

Poor 265 342 295 275 270 300 272 186 344 262 251 242 Unworked struc- 288 342 320 290 285 335 328 208 370 272 272 262 $gf8$f i 320 352 365 335 2 400 362 250 s 360 bility (113 (110 (113 (114 (121 F.) F.) F.) F.) F.) Norma-Hofimann Oxidation Test (hrs. to 5 p.s.i. drop) 400 250 365 360 Water solubility (boiling water) Nil Nil Nil Nil Nil Timken Test (lbs. carried) 40 50 40 40 40 40 40 50 Failed Failed 0 Scar Nar- Nar- Nar- Narrow row row row Almen Test- Gradualloadiur 15 15 Shocklnarlim 15 15 Failed 15 Wheel hearing test (660 a r.p.m. Pass Pass Pass Pass Stabilityin storage Crust formation" None None None None None 1 Excellent, smooth, uniform.

It will be seen that a wide variety of medium molecular weight carboxylic acids can be employed in conjunction with acetic acid and with conventional grease-forming, high molecular weight carboxylic acids to prepare grease thickeners, which have the ability to impart outstanding structural stability and extreme pressure properties to the final grease compositions. It should also be noted that only the soap-salt complexes wherein the carbon atom spread between the medium and the high molecular weight carboxylic acids was as least 7 and wherein theaverage saponification value of the medium and the high molecular weight carboxylic acids was from about 290 to 450' showed the desired results. Grease Nos. A and M, for example, having either carbon atom spreads or equivalent saponification values outside the operable ranges had either poorer structuralstability or extreme pressure properties than the greases of the invention.

EXAMPLE II A number of lubricating oil compositions containing furoic acid as an acidic constituent in the thickener and having the constituents and properties listed in Table 11 below were prepared as follows:

Composition No. A

grease batch'cooled further to 180200 F. The grease was then homogenized in a Gaulin homogenizer at 6000.

psi, filtered and packaged.

Composition No. B

This composition was prepared by the method substantially as described in the preparation of Composition N0. A, except that no acetic acid was employed.

Composition No. C

place of the hydrated lime and no acetic acid was/employed.

The exact constituents and properties of the above compositions are tabulated in Table II below:

TABLE II Composition No. A B (J Formulations (Wt. Percent):

Glacial acetic acid 12. 0 Hydrofol Acid 51 3.0 v 8.0 10.0 Furoic acid 3. 0 4. 0 5. 0 Hydrated lime 9. 8 5. 0 Sodium hydrox 4. 8 4 Pheuyl alpha naphthylarnine. 0. 5 O. 5 0. 5

Mineral lubricating oil (55 SUS/210 F.) 79. 7 M01 Ratio (acetic acid to higher acids) Saponification No. of acids (Ex acetic) Carbon atom spread (Medium to higher acid) Free alkalinity (Percent NaOH 4.-.." Propertiesr Appearance 'Dropping Point Penetrations (77 F., mm./

Unworked Worked strokes). Worked (100,000 strokes)" Water solubility (boiling Water) Timlcen Test Load- 50 lbs 0 40 l 1 Commercial stearic acid in the form of hydrogenated fish oil'acid. 2 Excellent, stable grease. r 3 No grease structure.

At the concentrations shown in Composition No. Buosatisfactory grease composition was obtained by employing the calcium salt of. furoic acid in combination with the normally grease forming metal soaps oflhigh molecular weight carboxylic acids e.g. ,stearic acid, in the grease thickener.

v It will be seen, however, fromCompositionNo: lubricating grease compositionspcan bejrepareld from a thickener comprising the calcium salt of'furoicac'i calcium salt of acetic acid, and the calcium soap of stearic acid. The complex thickener resulting from this combination of acids gives an excellent stable grease product having a high load carrying capacity. 7

Composition No. C illustrates that greases can be prepared from a thickener comprising sodium furoate and sodium stearate, but they show little load carrying capacity. This grease, for example, failed the Timken test at a 20 lb. load.

EXAMPLE III The use of commercial mixtures of medium molecular weight acids, e.g. Neo Fat 360 which is composed of 60 wt. percent caprylic acid and 40 wt. percent of capric acid, is exemplified by this experiment. The grease was prepared by the method described in the preparation of Composition A, of Example II.

The composition and properties of the final grease composition are tabulated in Table III below:

TABLE III Formulation Wt.

Percent Glacial acetic acid Neo Fat 300 Hydroiol Acid 51 Hydrated lime Phenyl alpha naphthylamiu Mineral lubricating oil (55 SUB/2 M01 ratio (acetic to higher acids) Saponification No. of acids (Ex acetic)- Carbon atom spread (medium to higher acids) Properties:

Appearance Dropping Point F.) Penetrations (77 F., mm.ll)-

Unworked Worked (60 strokes) Worked (100,000 strokes). Water solubility (boiling Wat Timken Test (40 lbs. load).-.

00% caprylic acid; 40% capric acid; sap. value (mg. ROE/gm.)- 355 6.

I Excellent, uniform grease. 3 Pass (narrow scar).

EXAMPLE IV The mineral lubricating oil, hydrated lime, stearic acid and citric acid were charged to a fire heated kettle and warmed to 135 F. while stirring. The acetic acid is then added, and the ingredients further heated to 500 F. The grease batch is cooled to 250 F. While agitating, and the phenyl alpha naphthylamine added. The grease is further cooled to below about 180 F. and then Gaulin homogenized at 6500 p.s.i.

Grease N0. 2

This grease was prepared by the method substantially as described in the preparation of Grease .No. 1 with the exception that 1.0 wt. percent rather than 2.0 wt. percent of citric acid was employed.

The composition and properties of these two greases are tabulated below in Table IV.

TABLE IV Formulation (Wt. Percent) 1 2 Glacial acetic acid 12. 0 10.0 Stearic acid 4. 0 4. 0 Citric acid 2. 0 1. 0 Hydrated lime l0. 0 8. 2 Phenyl alpha naphthylamine 0. 5 0. 5 Mineral lubricating oil (55 SUS/2l0 F.) 71. 5 7G. 3 M01 ratio of acetic to higher ncids 8.5 8. 8 Saponifieatiou No. (Ex acetic acid) 397 318 Carbon atom spread (Medium to higher acid). 12 12 Properties:

Appearance Dropping Point (F.) 500+ 500+ Penetration (77 F. mm./10)

Unworked 245 255 Worked (60 strokes) 285 290 Worked (100,000 strokes) 2 300 270 Water solubility (boiling water). Nil Nil Timken Test (40 lbs. load) Almen Test (15 wgts. shock load) Pass Pass Norma Hoilmann Oxidation Test (hrs. to

5 p.s.i. drop)..- 400+ 400+ Wheel Bearing 220 F.) Pass Pass 3 Pass (narrow scar).

EXAMPLE V The use of phthalic anhydride as a source of the medium molecular weight carboxylic acid constituent of the grease thickener of the invention is demonstrated by the grease prepared as follows:

The mineral lubricating oil, hydrated lime, stearic acid and phthalic anhydride were charged to a fire heated grease kettle and thoroughly mixed while warming to F. At this temperature the aqueous solution of acetic acid (80 wt. percent of acetic acid) was added, and heating was continued to 510 F. The heating was then discontinued, and the grease cooled to 250 F. with stirring. Phenyl alpha naphthylamine was then added, and the grease batch was further cooled to 180 F. The grease was then Gaulin homogenized, filtered and package The formulation and properties of the final grease composition are tabulated in Table V below:

TABLE V Formulation 1 Excellent, smooth grease.

EXA MPLE VI A lubricating grease containing a grease thickener prepared with hydroxy -bi1ZOiC acid as the medium weight carboxylic acid constituent was prepared by the method described above in preparing Grease H of Example 1, except that hydroxy benzoic acid rather than benzoic 13 acid was employed as the medium molecular weight carboxylic acid.

The composition and properties of the grease are tabulated in Table VI below:

TABLE VI Formulation Wt. percent Glacial acetic acid 12. Ste-aric id 3. 0 Hydroxy benzolc acid 3. 0 Hydrated lime 9. 2 Phenyl alpha naphthylamine 0. 5 Mineral lubricating oil (55 SUSI210 F.).. 72. 3 Free alkalinity (percent NaOH) 0. 33 M01 ratio (acetic to higher acids) Saponitication No. of acids (Ex acetic acid 300 Carbon atom spread (Medium to higher acid) 11 Properties:

Appear nce Dropping Point F.) 600+ Penetrations (77 F. mm.l)-

Unwor 290 Worked (60 strokes) 275 Worked (100,000 strokes) I 342 Water solubility (boiling viate Nil Timken Test (40 lbs.) Pass 1 Excellent, smooth, uniform. 1 108 F.

In brief summary, the present invention relates to soap-salt complexes comprising a metal salt of acetic acid, a metal salt of a medium molecular weight carboxylic acid containing from about 3 to 10 carbon atoms, and a metal soap of a high molecular weight carboxylic acid containing from about 12 to 22 carbon atoms. The preferred soap-salt complexes of the invention also have a carbon atom spread between the high and medium molecular weight carboxylic acid of at least 7 and an average saponification value of acids, other than acetic acid of between about 290 to 450. In addition the mol ratio of acetic acid to the medium and high molecular weight carboxylic acids is between about 4:1 to 40:1. In general, the mol ratio of medium to high molecular weight acids will be about 0.521 to 10:1, preferably about 1:1 to 9:1.

Lubricating grease compositions of this invention contain complex thickeners prepared from about 4 to 20 wt. percent, preferably 8 to 12 wt. percent of acetic acid, from about 0.5 to 8 wt. percent, preferably 2 to 4 wt. percent of the medium molecular weight carboxylic acid; and from about 0.5 to 10 wt. percent, preferably 1 to 5 wt. percent of the high molecular Weight carboxylic acid, the above weight percentages being based on the total weight of the grease composition. Ordinarily, a major proportion of acetic acid will be employed in amounts up to or higher than twice the combined weight percentages of the other two acids. The metal hydroxide and/or carbonate employed, e.g. lime, will be employed in amounts from about 5 to 12 wt. percent, based on the total weight of the grease composition.

The invention is not limited to the specific conditions and materials of the foregoing examples. These conditions and materials may be varied within the limits indicated in the general portions of the specification. The compositions prepared in accordance with the invention may contain various conventional additives, such as oxidation inhibitors, metal deactivators, corrosion preventatives, extreme pressure agents, dyes, deodorants, etc. as will be understood by those skilled in the art.

What is claimed is:

1. A lubricating grease composition which comprises a lubricating oil thickened to grease consistency within the range of 5 to 40 wt. percent of a complex of a metal salt of acetic acid, a metal salt of a medium molecular weight carboxylic acid containing from about 3 to 10 carbon atoms, and a metal soap of a high molecular weight carboxylic acid containing from about 12 to 22 carbon atoms, wherein the mol ratio of acetic to the other carboxylic acids is at least 4:1, the mol ratio of medium to high molecular weight acids is in the range of 0:5:1 to 10:1 the average difference in number of carbon atoms per molecule between the high and the medium molecular weight carboxylic acids is at least 7, the metal constituent of said soaps and salts is selected from the group consisting of alkaline earth metals and zinc, and said complex is prepared at a temperature in the range of 400 to 550 F.

2. The lubricating grease composition of claim 1 wherein said metal constituent is calcium.

3. The lubricating grease composition of claim 1 wherein said lubricating oil base is a mineral lubricating oil.

4. The grease composition of claim 1 wherein said high molecular weight carboxylic acid contains 18 to 22 carbon atoms.

5. A lubricating grease composition which comprises a mineral lubricatnig oil thickened to grease consistency within the range of 5 to 40 wt. percent of a complex prepared at a temperature in the range of 400 to 500 F. of a calcium salt of acetic acid, a calcium salt of caprylic acid and a calcium soap of hydrogenated fish oil acid, wherein the mol ratio of said acetic acid to said caprylic acid and said hydrogenated fish oil acid is about 5:1 and the mol ratio of said caprylic acid to said hydrogenated fish oil acid is about 6:1.

6. The method of preparing a lubricating grease composition which comprises dispersing a metal base, a medium molecular weight carboxylic acid containing from about 3 to 10 carbon atoms and a high molecular weight carboxylic acid containing from 12 to 22 carbon atoms in a dispersing proportion of a mineral lubricating oil, heating the dispersion to a temperature of about to F., adding acetic acid to the dispersion, and heating the resulting mixture to a temperature of about 400 to 550 F., the mol ratio of acetic to the other carboxylic acids being at least 4:1, the mol ratio of the medium to the high molecular weight acids being in the range of 0.5 :1 to 10:1, the metal constitutent of said metal base being selected from the group consisting of alkaline earth metals and zinc and the total amount of soaps and salts in said composition being in the range of 5 to 40 wt. percent.

7. The method of claim 6 wherein the medium molecular weight carboxylic acid is added to the dispersion with the acetic acid after heating the dispersion to a temperature of about 130 to 150 F.

8. The method of claim 6 wherein the resulting grease composition is homogenized.

References Cited in the file of this patent UNITED STATES PATENTS 1,752,309 Rosenbaum Apr. 1, 1930 2,215,955 Cox Sept. 24, 1940 2,274,675 Earle Mar. 3, 1942 2,468,099 Morway Apr. 26, 1949 2,487,080 Swenson Nov. 8, 1949 2,606,153 Holdstock Aug. 5, 1952 2,607,735 Sproule et a1 Aug. 19, 1952 2,618,599 King et a1. Nov. 18, 1952 2,628,195 Allison Feb. 10, 1953 2,735,815 Morway Feb. 21, 1956 2,846,392 Morway et al Aug. 5, 1958 OTHER REFERENCES Amott and McLennan: Article in The Institute Spokesman, vol. 14, No. 12 (March 1951), pages 7-23. 

1. A LUBRICATING GREASE COMPOSITION WHICH COMPRISES A LUBRICATING OIL THICKENED TO GREASE CONSISTENCY WITHIN THE RANGE OF 5 TO 40WT. PERCENT OF A COMPLEX OF A METAL SALT OF ACETIC ACID, A METAL SALT OF A MEDIUM MOLECULAR WEIGHT CARBOXYLIC ACID CONTAINING FROM ABOUT 3 TO 10 CARBON ATOMS, AND A METAL SOAP OF A HIGH MOLECULAR WEIGHT CARBOXYLIC ACID CONTAINING FROM ABOUT 12 TO 22 CARBON ATOMS, WHEREIN THE MOL RATIO OF ACETIC TO THE OTHER CARBOXYLIC ACIDS IS AT LEAST 4:1, THE MOL RATIO OF MEDIUM TO HIGH MOLECULAR WEIGHT ACIDS IS IN THE RANGE OF 0:5:1 TO 10:1 THE AVERAGE DIFFERENCE IN NUMBER OF CARBON ATOMS PER MOLECULE BETWEEN THE HIGH AND THE MEDIUM MOLECULAR WEIGHT CARBOXYLIC ACIDS IS AT LEAST 7, THE METAL CONSTITUENT OF SAID SOAPS AND SALTS IS SELECTED FROM THE GROUP CONSISTING OF ALKALINE EARTH METALS AND ZINC, AND SAID COMPLEX IS PREPARED AT A TEMPERATURE IN THE RANGE OF 400* TO 550*F. 